1. Field of the Invention
The present invention relates to design supporting of an electronic equipment.
2. Description of the Related Art
When signal lines extend parallel to each other, and their parallel distance is large, their signals influence each other, thus generating noise. Such noise is called “crosstalk noise”, causes a malfunction of a semiconductor device such as an IC (integrate circuit) or LSI (large-scale integration), and is emitted from a cable to induce spurious emission. In order to avoid such problem, a crosstalk noise countermeasure in a design stage is required.
As a method of verifying a malfunction of an electronic equipment due to crosstalk noise, a method of acquiring wiring information from layout information of a print circuit board, and verifying a distance between a signal line through which a high-speed signal flows, and a signal line which is influenced by crosstalk noise is known. A wiring on the side which gives crosstalk noise will be referred to as “aggressor wiring” hereinafter, and a wiring on the side where the influence of crosstalk noise is received will be referred to as “victim wiring” hereinafter.
The following technique has been proposed. That is, a shortest distance (permissible distance) from a high-speed digital signal line is set in advance, and a signal line (neighboring wiring) which is disposed at a position closer than the permissible distance is extracted while focusing attention on a conductor pattern through which a high-speed digital signal flows. Furthermore, a length (permissible length) of the neighboring wiring is set in advance, and when a length of the extracted neighboring wiring exceeds the permissible length, that neighboring wiring is detected as a design violation.
Various problems caused by crosstalk noise occur not in an aggressor wiring but in a victim wiring. Therefore, according to the aforementioned verification method which focuses attention on an aggressor wiring, even a victim wiring which hardly causes a problem even if it is influenced by crosstalk noise may be detected, and design violations may be excessively detected.
Focusing attention on a victim wiring, there are a victim wiring which receives an influence that induces a malfunction of a semiconductor device and a victim wiring which suffers a problem of an electro magnetic interference from a cable. Especially, a victim wiring which suffers a problem of the electro magnetic interference (EMI) from a cable is normally a signal line connected to a connector. However, a large number of signal lines are connected to the connector, and signal names of the signal lines connected to the connector are often automatically appended by CAD (Computer Aided Design). For this reason, much time is required to manually extract the signal lines so as to verify the signal lines which suffer a problem of the electro magnetic interference from a cable, and are connected to the connector, thus causing extraction mistakes and extraction errors.